gen. nov., sp. nov., a novel member of the family .

Strain ISS155, isolated from surface Mediterranean seawater, has cells that are Gram-reaction-negative, motile, strictly aerobic chemoorganotrophic, oxidase-positive, unable to reduce nitrate to nitrite, and able to grow with cellulose as the sole carbon and energy source. It is mesophilic, neutrophilic, slightly halophilic and has a requirement for sodium and magnesium ions. Its 16S rRNA gene sequence places the strain among members of , in the , with 017 as closest relative (94.3 % similarity). Its major cellular fatty acids are C, C and C; major phospholipids are phosphatidyl glycerol, phosphatidyl ethanolamine and an unidentified lipid, and the major respiratory quinone is Q8. The genome size is 6.09 Mbp and G+C content is 45.2 mol%. A phylogenomic analysis using UBCG merges strain ISS155 in a clade with , , and type strain genomes, all of them possessing a varied array of carbohydrate-active enzymes and the potential for polysaccharide degradation. Average amino acid identity indexes determined against available type strain genomes show that strain ISS155 is related to them by values lower than 60 %, with a maximum of 58 % to 017 and 57 % to T7902 and 2-40. These results, together with the low 16S rRNA gene sequence similarities and differences in phenotypic profiles, indicate that strain ISS155 represents a new genus and species in , for which we propose the name gen. nov., sp. nov., and strain ISS155 (=CECT 9533=LMG 31237) as the type strain.